1. Field of the Invention
The present invention relates to a pump assembly.
2. Description of Related Art
There have been developed "dry" cleaning systems that utilize a liquefied gas such as carbon dioxide (CO.sub.2) as a cleaning fluid. Liquefied gas based cleaning systems include a pump that circulates the liquefied gas through a cleaning vessel. Conventional pump assemblies contain a motor that drives a pump device such an impeller. To avoid fluid contamination, the motor is located in a housing chamber external to the impeller of the pump. The pump housing typically has a seal to separate the motor from the liquid gas.
Liquid CO.sub.2 is typically pressurized to a level of approximately 800 psi. It has been found that highly pressurized liquefied gas will leak past the pump seal and into the motor chamber. The aggressive cleaning action of the liquefied gas removes the grease and lubricants within the motor, thereby reducing the life of the pump assembly. It would be desirable to provide a liquefied gas pump assembly that prevents the liquefied gas from "cleaning" the motor of the assembly.